Valve-gear for oscillating engines



UNTTED sTATEs PATENT g oEEIoE.

D. DU BOIS, OF NEWBURG, NEW YORK.

VALVE-GEAR FOR OSCILLA'IING ENGINES.

Specification of Letters Patent No. 12,904, dated May 22, 1855.

'- hereby declare that the following is a full,

clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification,

' in which- Figure l, is a central sect-ion of a horizontal oscillating engine with my improved valve motion applied. Fig. 2, is an elevation of the valve motion with a section of the valve. Fig. 3, is an elevation of a part of the valve motion and section of the valve in a position different to Fig. 2. Fig. 4, is a top view of the valve motion. Figs. 5 and 6 are portions of the mechanism of the valve motion detached from the engine.

Similar letters of reference indicate corresponding parts in the several gures.

A, is the cylinder; B, the steam chest; and C, a double slide valve of well known character. The steam is supposed to enter the steam chest through one trunnion, and from thence into the cylinder through the ports a, and a', alternately, exhausting through the ports b, and o', to the other trunnion.

E, is a rockshaft passing transversely throughthe steam chest, in the sides of which suitable bearings are provided for it,

and carrying within the steam chest aA toothed segment F, which gears with a toothed rack on the back of the valve. rIhe said rockshaft also carries a three armed lever c, d, d1, shown detached in Fig. 5, of which a line through the center of the lower arm c, continued through the axis of the rockshaft would bisect the angle formed by the lower arms CZ, rl', and between that lever and the steam chest it carries another three armed lever e, f, f', shown detached in Fig. 6, of which the uper arm e, or handle stands directly in the opposite direction with the arm c, of the other lever and the two lower arms f, f', stand at corresponding angles with the arm c. Both the above levers are secured firmly to the shaft.

G, is a standard secured to the bed plate of the engine and striding over the trunnion. This standard carries a vertical sliding piece H, in which is secured a stud g, standing directly over the center of the trunnion. This stud is for the purpose of moving the valve to open the ports, which it do-es by its operation on the arm c, as the said arm is carried past it by the oscillation of the cylinder.

The standard G, also carries two spring catches 71 L, which are caused by the oscillation of the cylinder to act upon the arms f, f', to move the valve to close the ports; and in addition to these spring catches the said standard also carries two {ixed but ad- Justable pieces z', i', against which the arms el, CZ", strike if necessary to throw the arms f, f', over and into engagement with t-he spring catches h, h. These pieces z', c", are furnished with springs y', y, upon which the arms f, f, strike to prevent too great concussion.

To illustrate the operation of the valve I will first suppose the crank to be rotating in the direction of the arrow shown in Fig. l, but the engine to be on the center, and about to take steam at the left hand end of the cylinder; the arm c, is then in contact with the right side of the stud g, as shown in Fig. 3, and as the cylinder oscillates in the direction shown in Fig. l, the arm c, is moved to turn the rockshaft in the proper direction for the segment F, to move the valve in the proper direction to open the port a, the full opening being effected early in the stroke and the valve being subsequent-ly left stationary in the position shown in Fig. 1, by reason of the arm c, passing over and working clear of the stud g. As the cylinder terminates its oscillation the arm f, passes the hook of the spring catch L, and is caught by it, so that as the cylinder returns toward a.A central position, the catch acts upon the said arm f, to move the valve to close the po-rts after which the arm works clear of t-he catch. In Fig. 2, the ports are represented as being just closed and the arm f, to be just working clear of the catch h. The engine is now nearly on its center, and the arm c, is just' coming in contact with the left side of the stud g, to move the valve to open the port a', to the steam. If the valve is not moved far enough by the stud g, to bring the arm f, or f, as the case may be, in position to be caught by the spring catch h, or h, the catching will be ensured by the arm CZ or (l, on the same side striking the piece h or h-, and throwing the arm over the hook of t-he catch. This will only be necessary when the valve has a short stroke. The length of stroke of the valve may be varied by moving the sliding piece H, with its stud g, higher or lower, theraising ofthe stud giving a longer stroke and vice versa. A lever I, is attached to the standard G, t-o raise 0r lower the sliding piece for this purpose. The same lever serves to stop and start the engine as by lowering the stud so that the arm 0, will clear it the movement of the valve will be stopped entirely. The time of closing the ports may be varied by shifting the spring catches z, L, and adjustable pieces z', z'.

This valve motion is just as well applicable to puppet or cock valves as to the slide valve. Two puppet or cock valves may be worked by separate rockshafts operated by two rods connected with the arm or handle e, and a reverse movement may be then given by shifting the connection of each rod from one to the other of two opposite arms on each of the said separate rock shafts in a similar manner to that in which the reversal is now sometimes eiected with the eccentric valve gear of locomotives.

What I claim as my invention and desire to secure by Letters Patent, is-

l. Furnishing the rockshaft E, by which motion is to be given to the valve or valves with three arms c, f, f arranged substantially as described, so that the arm c, will be brought by the oscillation of the cylinder into .contact with a fixed stud g, and thereby be caused to give a movement to the valve to open the ports, and that the arms f, f', will alternately be brought by the same means into Contact with fixed spring catches 7i, h, for the purpose of giving the valve. a movement to close the ports as herein fully set forth. v

2. I claim furnishing the rockshaft with two arms 6l, d', arranged substantially as described to strike two fixed pieces z', z', when necessary to throw the arms f, f, into a pom sition to be caught by the spring catches 7L, L, for the purpose of moving the valve to close the ports.

MARCUS D. DU BOIS.

Witnesses:

J os. GEO. MASON, WILLIAM TUsoH. 

